"When we started this show in 2003, the iPhone didn't exist. Social media didn't exist. Gay marriage wasn't legal," DeGeneres said last month, after pre-taping the show's final episode.
"We watched the world change -- sometimes for the better, sometimes not."
There is no doubt the cultural landscape has been upended since rising comedian DeGeneres came out in 1997 -- simultaneously as her character on sitcom "Ellen," and in real life with an interview on the cover of Time magazine.
DeGeneres was hailed as a gay icon, but her sitcom was cancelled a year later amid a backlash, and she spent five years in the wilderness before reinventing herself as a talk show host.
"It was a sensation, it was a landmark -- and it became a political football," said Mary Murphy, associate professor of journalism at University of Southern California.
"She led the way. She was probably -- and may still be -- the most famous LGBTQ person in America."
No 'gotchas'
While DeGeneres has never shied away from her sexuality, her Rolodex of A-list guests and light touch have been key to the talk show's success, especially in more conservative parts of America.
For 19 seasons, Hollywood A-listers and pop stars have jostled for seats on DeGeneres' couch, where they are invited to promote their latest projects, and never put through more than a gentle ribbing.
Some have appeared more than a dozen times -- Jennifer Aniston, the show's first-ever guest, will return for Thursday's finale.
"She is one with the celebrities, she's their friend. They know that. And she made it jovial," said Murphy.
"Maybe it was because, having been so burned, as she was, she didn't want to burn other people. There were no gotchas."
Audience members and the latest viral YouTube stars are also regularly invited on stage to enjoy their 15 minutes of fame, in human interest segments and wacky games.
"Ellen is this funny, silly, quirky character that really didn't take herself too seriously," said Jeetendr Sehdev, author of "The Kim Kardashian Principle."
"We hadn't quite seen a daytime talk show host before that looked like her and that behaved like her... She was the cropped haired woman wearing a suit and tie while everyone else was getting blowouts."
'Full of contradictions'
But rumors that life was less rosy backstage came to a head with a 2020 Buzzfeed expose alleging a "toxic work culture" including sexual harassment, bullying and racism.
Three senior producers were fired, while DeGeneres was accused of failing to mind her shop -- and of being less affable with employees in private than her cheery public persona would imply.
Last May, DeGeneres announced the show would end after its 19th season, but denied it was due to the workplace claims.
"I need something new to challenge me," she told The Hollywood Reporter.
But DeGeneres has courted increasing controversy, including her defense of comedian Kevin Hart after he withdrew as Oscars host in 2018 over a series of homophobic tweets.
"Suddenly, she kind of fell from grace," said Murphy.
"She seemed to be... in touch with celebrities, in touch with audiences, out of touch with the people working for her."
According to Sehdev, Ellen has always "been full of contradictions."
"That has been both partly the reason why she has also appealed to people, and has been capable of generating that mass appeal," he said.
"And at the same time, (it) has also been the reason why her integrity and her credibility and authenticity have been questioned."
